1. Technical Field
The present invention relates to a polymerizable yellow dye. More particularly, the present invention relates to a polymerizable yellow dye for manufacturing ophthalmic lens which is capable of blocking or lower the intensity of blue light transmitted through ophthalmic lens.
2. Description of Related Art
Solar radiation is one of the primary hazardous factors to human vision. Ultraviolet (UV) light, visible light and IR radiation from the sun is mostly absorbed by the atmosphere. The solar radiation penetrating through the atmosphere and reaching the earth's surface mainly consists of UV-A radiation (wavelength at 300-400 nm), visible light (wavelength at 400-700 nm) and near IR radiation (wavelength at 700-1400 nm). A healthy ocular media of man can block the solar radiation in near IR and most of the visible spectrum to the retina.
In recent years, blue light (wavelength at 400-500 nm) of visible light has been recognized as potentially hazardous to the retina. In the nature, most of blue light is from sun. Moreover, most of electronic products, such as liquid crystal display, light-emitting diode lamp, cell phone panel and computer monitor, have a backlight source with high efficiency of blue light. The blue light can damage the retina and increase the probability of macular degeneration, an irreversible damage to the vision might occur.
In this regard, yellow dyes have been used to block blue light so as to avoid potential damage of the blue light. However, conventional yellow dyes are water-soluble and limited only to the ophthalmic lens made from hydrogel, but cannot be used in the ophthalmic lens made from silicon hydrogel. With the advent of increasing popularity of the ophthalmic lens made from silicon hydrogel, new materials are needed in minimizing or eliminating such risks associated with the exposure of the blue light. Therefore, there is still a need for a novel polymerizable yellow dye for manufacturing ophthalmic lens.